Method of testing protective coatings



June 22, 19435 H! c. DE sTAEBLER 2,322,228

METHOD OF TESTING PROTECTIVE commas Filed. July 51, 1941 HERBERT C.DESTAEBLER v INVENTOR ATTO RN EY Patented June 22, E43

PATENT OFFICE METHOD 9F TESTING PROTECTIVE COATINGS Herbert G. DeStaebler, Kirkwood, Mo.

Application July 31, 1941, Serial No.- 404,858

6 Claims.

generally contain ingredients which re-act chemically with some of theless expensive available metals which are otherwise suitable for theconstruction of thin walled collapsible tube containers to causeobjectionable discoloration and contamination of the paste. It has beenfound, however, that an unbroken protective coating such as lacquerapplied to the interior of the tube containers provides a satisfactorymeans of preventing contact between the paste and the metal and permitsthe use of such metals as lead or aluminum which would otherwise causecontamination of the paste. It is highly essential, however, that thiscoating be continuous and unbroken as a relatively small break in thecoating, not obvious upon visible inspection, would cause considerablecontamination.

The present invention has for its primary object the provision of aninexpensive and reliable device for testing the continuity of suchcoatings and which includes a signaling device automatically operativeupon detection of a break in the coating.

It is a further object of the present invention to so arrange, incombination, a device of the above character and an automatic tubefilling and closing machine that full automatic operation of the testingdevice is attained.

Other objects and advantages will appear upon reference to the followingdescription and ac companying drawing in which Fig. 1 is aperspectiveview or" an automatic tube filling and closing machine havingattached thereto a testing device constructed in accordance with thepresent invention.

Fig. 2 is an enlarged view of a portion of the machine shown in Fig. 1having a somewhat diagrammatic arrangement of the testing devicecircuits shown therewith.

Fig. 3 is a sectional view taken on line 3-3 of Fi 2.

The tube filling and closing machine illustrated in Fig. 1 is of modernconstruction and of the type which employs a conveyor system comprisinga train of separate block-like carriers l,

which are slidable vertically independently of each other and are movedhorizontally in 'guideways 2 and 3. The carriers move from right to leftin the guideway 2 and their direction is reversed at the ends of theguideways by means of the turntables 4 and 5. A hopper t for storing thepaste to be packed is provided and a multiple tube filling head isindicated at i. Socket-like holders 8, attached to the upper surface ofthe carriers I, to receive the tubes to be fllledare provided.

In the machine illustrated the filler head carries four nozzles 9. Thepaste is discharged under pressure from these nozzles and the dischargeis controlled by valves therein not shown, which are operated by pushrods to. Means for applying pressure for the ejection of the paste fromthe nozzles 9 is not shown. but it will be understood that such means isincorporated in moderntube filling machines of the type indicated inFig. 1. The carriers are moved vertically by cam means H as they moveinto line with the filler head and the nozzles 9 enter the containertube l2 so that filling may start from the lower end. It is immaterialas far as the present invention is concerned whether the container tubesare moved upward to admit the nozzles or whether, as in other machines.the filler head is movable vertically and wherein the nozzles are moveddownward into the container tubes.

The container tubes l2 are constructed of metal, such as lead oraluminum having relatively high conductivity and are provided, on theirinner surfaces I3, with a continuous and unbroken protective coatingsuch as lacquer or the like, and are impervious to the paste they are tocontain and having relatively high dielectric strength. As it isobviously a difllcult matter to visibly inspect suchcoatings for breaks,I propose to inspect them electrically by means of the followingarrangement:

The filler tubes 9 are constructed of a non-conductive material,preferably one of the commercial thermo-plastics, and. carry attachedthereto electrodes I4 which comprise a pair of conductive bands l5 andI6 and a conductive connector strip it. The upper bands l6 are providedwith studs it for the connection of leads. A source of electrical energyis indicated in the form of a storage battery at H. A closed batterycircuit 20 including a resistor 2| and a slidable take-off arm 22provides a means for applying a variable potential at the electrodes M.The electrodes H are connected to slidable arm 22 by individual leads 23and the common lead 24. It is desired to point out at this time thatcommercial tooth pastes and shaving creams have been found to be fairlygood conductors of electricity.

The container tubes 82 contact, at their lower ends, the shoulders 25formed in the sockets 8 and it will be understood that the tubes aregrounded through these sockets and the machine. It is of particularadvantage in the present arrangement to attach the electrodes to thefiller nozzles 50 that the coatings may be subjected to electricalpressure at a time when the paste is being discharged, as at this timethe lower end of the tube is reacting with considerable pressure againstshoulder 25 to form a good contact for grounding the tubes. Connected inthe iiiin that the relays 26 may be made highly sensitive, which isobviously essential, without danger of their vibrating as would be thecase when operated on alternating current.

In operation: The empty container tubes are inserted in the sockets 8 bythe operator. As they move into register with the filling head they aremoved upward as indicated in Fig. 2 and paste is discharged underpressure from the nozzles 9. At this time a predetermined voltage isimpressed upon the inner coating of the tube, the intensity of which hasbeen predetermined by cpnsiderations involving the strength of suchcoating when or suitable thickness, "the conductivity of the paste andthe-diameter of container tubes. The intensity of'the impressed voltagebeing varied by adjusting the sliding take-oil arm 22.

If the coating of any tube breaks down under this impressed voltage, dueto a thin spot or break, sufficient current will fiow through thisparticular tube circuit to cause its respective relay to close thecircuit of a corresponding signal light. The signal light being arrangeddirectly above and in line with the respective tubes, the operatorsattention will be directed to the faulty tube which may then be removedfrom the conveyor.

If it is packed are substantially better conductors than those atpresent anticipated, further ,steps may be taken to prevent grounding ofthe testing cirdielectric found that certain materials to be cult to themachine via the material within the filling tubes and hopper; such asinsulating the filling head and hopper from the machine by insertion ofan insulator at it and at any other points at which structural oroperative connections between the hopper and filler head and the machineare necessary.

The foregoing description and accompanying drawing are intended to beillustrative, not limiting, and the exclusive .use of all modificationswithin the scope of the appended claims is contemplated. I claim:

l.'In a machine for filling metal container tubes with a plasticmaterial and simultaneously testing the continuity of protectivecoatings applied to the interior of the tube, a tube conveyor systemincluding sociretdilre holders for receiving the tubes to filled attheir closed ends, a tube filling nozzle arranged to enter the tubes attheir open ends and to discharge plastic material thereinto, anelectrode attached to said nozzle and arranged to enter the tubes, saidtube holding sockets being of metal and being connected to the machineso as to electrically ground the tube, a source oi electrical energy, alead connecting said source oi energy with said electrode, electricallyoperated signaling device, and a device interposed in said lead andresponsive to a flow of current theretlnough for controlling saidsignaling device.

2. In a tube filling machine, a filler head carrying a plurality offiller nozzles, a tube conveyor. system for positioning the tubes to befilled in line with said nozzles, means for entering said nozzles intothe open ends of the tubes, an electrical system for testing protectivecoatings applied to the interior of the tubes comprising electrodesarranged to be entered into the tubes simultaneously with the fillernozzles, a source of electrical energy, independent leads connectingsaid source of energy with said electrodes, a variable resistor arrangedto vary the potential at said electrodes, means for grounding the tubesto be filled, electrically operated independent signaling devicemountedon said filler head in line with respective nozzles, andindependent relays in said leads for controlling said signals.

3. In a. tube filling machine, a filling nozzle arranged to be enteredinto the open ends of the v tubes to be filled and to dischargethereinto when so entered, an electrical system for testing protcctivecoatings applied to the interior of the tube comprising a source ofelectrical energy,

tube containers with a semi-fluid material, an,

electrical system for testing thin non-conducting protective coatingsapplied to the interior 0! the tube containers comprising a source ofelectrical energy, an electrode arranged to be entered into the tubecontainers and spaced from the walls thereof and in contact with thematerial in the tube, a lead connecting said electrode with said sourceof energy, means for grounding the container tubes by contact with theexterior thereof, asignaling device, and a relay interposed in saidlead'for controlling said signaling device.-

5. In a tube filling machine, means for filling tube containers with asemi-fluid material, an electrical system for testing the continuity ofthin non-conducting protective coatings applied to the interior of thetube containers comprising a source of electrical energy, an electrodearranged to be entered into the tube containers and in contact with thematerial in the tube, a lead connecting said electrode with said sourceof energy, means'for grounding the tube c0n-. tainer by contact with theexterior thereof, and a control relay interposed in said lead andoperable upon a flow of current therethrough' occasioned by a fault inthe coating.

6. In a container filling machine, means for filling the containers withthe material to be packed, an electrical system for testing thecontinuity of thin, relatively non-conductive protective coatingsapplied to the interior of the containers comprising a source ofelectrical energy, an electrode arranged to be entered into thecontainers and in contact with the material therein, a lead connectingsaid electrode with said source of energy, means for grounding thecontainers by contact with the exterior thereof, and a control relayinterposed in said lead and operable upon a how of current therethroughoccasioned by a fault in the coating.

HERBERT C. DE STAEBLER.

